Gina is a human girl and the primary owner and caretaker of the title character in the 1988 anime adaptation of Topo Gigio. She lives in the town of Catharina, where she encounters the mouse astronaut after his spacecraft malfunctions and becomes stranded on modern Earth. Gina is described as being nine years old.

Her role in the story is central, as she is the one who adopts Topo Gigio, providing him with a home and forming the core of his new life on Earth. She is depicted as a kind and compassionate child, taking in the lost and unusual mouse without hesitation. Her home becomes a sanctuary for Gigio and his friends, placing her directly in the path of the series’ primary conflict. Gina also owns a white female mouse named Mimi and a hamster also named Mimi, who lives in a cage. Other mice in Gigio's circle of friends, including Kurt, Pierre, and Arnold, are also part of her household or under her care.

Gina shares a close interspecies friendship with Topo Gigio. A defining and notable aspect of their relationship is that Gigio is the only animal in the series who can speak directly with humans, and Gina is the principal human he communicates with. She offers him advice and hope during difficult moments, and he, in turn, becomes a source of support and companionship for her. The series presents their bond as one of mutual comfort, with Gina acting as a protector and confidante to the small, futuristic mouse.

Her personal life is defined by the environment she lives in. The same building where Gina resides is also home to an elderly woman named Mrs. Knopp, who owns Megalo, a large, aggressive black cat. Megalo harbors a deep hatred for mice and serves as the main antagonist, creating a constant source of danger for Gigio and his friends. As a result, Gina’s home is situated in the middle of this predator-prey dynamic. While her family background is not detailed, her mother is confirmed to appear in the series.